Control switch



oct. ze, 1937. J, s, DUNN 2,996,709

CONTROL SWITCH Filed March l0, 1936 Patented Oct. 26, 1937 CONTROL SWITCH John Struthers Dunn, Mount Airy, Philadelphia, Pa., assignor to Struthers Dunn Inc., Philadelphia, Pa., a corporation of Pennsylvania Application March 10,

4 Claims.

My invention relates to electrical control switches, particularly of that type effecting circuit rupture or closure by snap action.

In accordance with my invention there is associated with a toggle, or equivalent structure effecting snap action, a movable frame or equivalent structure to which, and not to the toggle, is applied through the contacts themselves the force which actuates or controls the toggle or equivalent structure.

Further in accordance with my invention the frame or equivalent structure may comprise pivoted elements pivotally tied to each other to insure their movement in unison; or may comprise f' elements secured in substantially fixed relation to each other and pivoted as a unit; more particularly, elements or sides of the frame or unit are disposed on opposite sides of and preferably extend substantially'parallel to one of the movable elements of the toggle or equivalent structure; and there are provided stops, for limiting the frame travel in either direction, which pref# erably are non-yielding or rigid and so serve, due to the impacts of the frame thereon, to deliver hammer blows thereto for insuring good makes and breaks at and between the frame contacts and the contact carried by the toggle or equivalent snap-action member.

Further in accordance with my invention there ccact with the frame in its actuation or control, springs, the tension or compression of one of which is changed upon application of the primary actuating or control force, representative of or responsive to pressure, temperature or other varying magnitude or condition,.to permit another of the springs to gain control of and actuate the frame in one direction, and upon subsidence of the primary force the frame is actuated in reverse sense; more particularly there coacts with the frame a member or rod with which one or more of-the aforesaid springs coacts in the control or actuation of the frame, and preferably force is applied to the frame by or through the rod in one sense or direction only; and more particularly there are provided means, preferably adjustable upon er with respect to the aforesaid rod or member, for varying or changing the coaction of the aforesaid springs or equivalent` means to determine at what magnitude of the primary actuating force the frame shall be actuated or controlled:

My invention resides in the features of construction and combination hereinafter described and claimed.

For an illustration of some of the various forms 1936, Serial No. 58,039 (Cl. 200-67) my invention may take, reference is to be had to the accompanying drawing, in which:

Figure 1 is a plan view, partly in section, of av control switch embodying my invention;

Fig. 2 is a plan view, partly in section, of a modified-form of my invention.

Referring to Fig. 1, within a housing there is secured a. block 2, of insulating material when the housing is of metal, in which there is a pivot recess 3 in which is pivoted at its one end the longer arm or link 4 of a, toggle. At its upper end the toggle element 4, in this instance of metal, is pointed or has a knife edge 5 engaging in a pivot recess or V-notch 6 at the lower end of the second toggle arm or'element 'I which at its upper end has a pivotal point or knife edge 8 engaging in the pivot recess or V-notch 9 in a plunger I Il, passing freely through the wall of housing I, thrust downwardly by spring II conned between the plunger I and the inner end of the screw I2 threadably adjustable in the sleeve I3 carried by the housing I.

In the position illustrated in Fig. 1 the toggle 4, I is in one of its extreme or"broken positions; its dead-center position, immediately to either side of which a snap action begins, corresponds with thecircumstances that the pivots at 3, and 8 are all simultaneously upon an imaginary straight line, or when the pivot 5 lies on the imaginary straight line extending from pivot 3 to pivot B.

Disposed on opposite sides of and preferably, f

as shown, parallel to and enclosing or embracing the toggle element 4 are the frame elements I4 and I5, in this instance of metal, pivoted respec- 3 tively at I6 and ,Il in upstanding portions of the metal brackets I8 and I9 secured to the block 2.

Secured tol and in conductive relation with the toggle element 4 is the switch contact 20 adapted to coact with the contacts 2i and 22 secured to and conductively connected with the frame elements I5 and I4, respectively. l To cause the frame members I4 and I S always to move in unison with each other, they are mechanically tied together by the member 22, of insulating material, pivoted to those members at 24 and 25.

Conductors 26, 2i and 2i, of the circuits to be opened and closed, connect respectively with the toggle element 4, and the aforesaid brackets I8 0 and I9, whereby the conductors 28, 21 and 28 are in electrical communication with the contacts 20, 2| and 22, respectively.

Screws 29 and 30, threaded through the opposite walls of housing In, have at their inner ends heads or stops 29a. and 30a for limiting the travel in either direction of the frame I4, |5 and of the toggle member 4. The screws 29 and 30 may be provided at their outer ends with screw-driver slots for eiecting their adjustments to desired positions, in which they may be held by lock nuts a good make at and between the toggle contact and either of the frame contacts 2|, 22; and the hammer blow contributes also to a good fbreak between the contact 23 and either of the frame contacts 2|, 22. Should the contact 20,

in the circuit-closing position illustrated, adhere tothe frame contact 22, due to mechanical stickingor from slight electrical fusing of the contacts to each other, upon actuation of the frame to cause the frame member I5 to impact against the stop 35a, the jar or hammer blow so imparted to the frame element I5 is communicated through the frame member I4 to contactf22 to break it loosefrom the contact 20 which then snaps across into engagement with contact 2|.

The circuit through conductors 26 and 28, shown as closed by virtue of engagement of contacts 20 and 22, may be opened by applying force to the frame I4, I5 to cause the upper end of the frame to move towards the left about the pivots I6 and In consequence pressure is exerted upon the toggle contact 20 through the frame contact 22. Contact 22 so in engagement with and pushing upon the contact 20 causes them to move together, maintaining stable, non-chatter- 'ing good contact, until the toggle member 4 reaches and slightly passes dead-center position, whereupon member 4 and its contact 20 snap toward the left, making a quick break as between contacts 22 and 20, the latter then coming into engagement with contact 2| on frame element I5, the parts coming to rest with the frame member I5 against stop 30a and frame member I4 separated from stop-29a.. During switch operation one of the frame contacts exerts pressure upon contact 20 at their engaging faces as effected by application of actuation or control of the frame as hereinafter described.

To open circuit at the contacts 2|! and 2| and to reclose it at 20, 22, force is applied in reverse sense to the frame I5, I4, causing action like, but the reverse of, that above described, terminating whenthe frame member' I4 again engages its stop 29a.

Structure of this type and mode of operation is characterized by the fact that the contact movable with snap action does not coact with a stationary contact; on the contrary the frame contact, which coacts with the contact of the toggle (or equivalent structure effecting snap action), itself moves, exerts pressure upon the toggle contact, and follows it with continuance of the pressure until inception of the snap action, whereupon the toggle contact quickly separates from the pressure-applying contact, rupturing the-circuit' with a quick, clean and sharply defined break.

During such application of force to the toggle or equivalent snap-action element and while at rest the coacting contacts maintain good and stable electrical contact with each other; they do not chatter on or with respect to each other,

`phon 31.

causes head 38 to exert a force toward the right.

as might otherwise occur' due to vibrations vtho in the switch structure or imparted thereto by forcible or heavy external vibrations, and so avoid substantial variations in resistance at the contacting faces, and so especially avoid small or minute circuit ruptures. The avoidance of chatter prevents damage to the contacts themselves, and eliminates eiects interfering with radio reception.

A further advantage resides in the wiping action upon each other of the coacting contacts vat their contacting vfaces while they move in engagement with each other until inception of the snap action. During their movement, they rub upon each other in the plane or surface of contact, by virtue of thefact the toggle element or equivalent and the frame or frame element are not pivoted about the same axis; and the wiping or rubbing action maintains the contact faces clean.

Generally the frame I4, I5 is actuated or controlled by application of force representative of or responsive to change in temperature, pressure or other condition or circumstance.

Reverting to Fig. 1, there extends freely through frame elements I4 and I5 and toggle element 4, a rod 3| surrounded by the helical spring 32 conned under compression between the frame element I5 and a collar or head 33 whose hub 33a. is secured, as by a pin, on rod 3|; there may be provided a disc 32a. upon 33 for centering the spring 32. l

Threaded on rod 3|, for adjustment thereon, is a member or nut 34 which through the insulation 34a abuts against 'the rounded or more or less knife-edge abutment 35 on frame member I4. Adjustment of nut 34 upon rod 3| varies or adjusts the effect of the spring'32, and so adjusts the point of response or actuation of the switch as affected by force exerted upon rod 3| in accord with temperature, pressure or some other condition or circumstance.

. Generically to illustrate means for exerting upon the rod 3| a force in accord with pressure, temperature or otheicondition, there is shown a thermo-responsive device comprising a tube 36 changes in temperature to which tube 36 is sub-1 jected, exerts corresponding fluid pressure upon the corrugated metal sylphon or bellows 3l, and its end or head 38, spaced from the walls of chamber 39 with which tube 36 connects. The chamber 39 is secured by screws 39a' to housing I. At the end of chamber 39 is a plate 40 closing the space within chamber 39 between it and the syl- The iiuid pres-sure exerted or applied The member or rod 3| extends through the wall of the housing I for movement to the right or left. At its left end the rod 3| is provided with a' head 4| between which and the housing wall is conned under compression a helical spring 42 adapted to thrust against the head tending to move the rod 3| toward the left. The head 4| abuts against the head 38 of the sylphon or bellows 31 or, in any event, is so related to thehead 38 that when fluid pressure exerted upon the sylphon increases, the head 38 forcesv the,head 4| toward the right, compressing or increasing the compression@ of the spring 42 so allowing the spring 32 to-Again control of and actuate the frame I4, I5 in one direction to cause actuation of the switch elements. Upon decrease or subsidence of the uid pressure the spring 42 expands and forces the rod 3| again containing a suitable uid which, in response to toward the left, overcoming spring 32, and causing actuation of the frame in opposite direction, correspondingly to actuate the switch in opposite sense.

The springs 42 and 32 are so related, and their relative tensions or compressions are such, that increase of fluid pressure upon the sylphon 31 causes compression or further compression of the spring 32 to cause actuation of the switching mechanism in one sense, and upon subsidence or decrease in the fluid pressure the net force applied to the frame causes actuation of the switch in opposite direction. The adjusting nut or member 34 serves to adjust the relation to each other of the tensions or compressions of the springs 32 and 42, and so in effect determine at what temperature or other magnitude of a condition or quantity the frame should be actuated in either direction.

While there are shown two contacts, 2| and 22, coacting with the movable contact 20, it shall be understood that if only one circuit is to be controlled, one or the other of the contacts 2|, 22 may serve merely as a button or member for pressing against the contact 20,and in such case one or the ,other of the conductors 21 or 28 would not be employed. In this connection, it shall be further understood structure of the character and mode of operation described may be utilized for controlling more than the two circuits which have been illustrated by way of example.

Any of the circuits controlled by the width of ythe character described may include any desired translating device, such as an electric lamp, or lamps, an electric motor, a heating resistance or any other electrical impedance, an electromagnet, a relay winding, or any other controlled or controlling device.

In Fig. 2 there is shown a modification, again illustrated, by way of example, as actuated or controlled by a thermo-responsive device such as illustrated in connection with Fig. 1.

In Fig. 2, 43 is a base or plate o! insulating material having marginal upstandlng integral members 43a over which may t a cover member, not shown, enclosing the entire mechanism except the thermo-responsive or other primary force-applying means, and excepting also the adjusting member hereinafter referred to.

.In this instance again the frame encloses or embraces the toggle structure or equivalent snap action device.

The longer toggle element or member 44, of metal, is provided with a. pivot 45 which at its inner end is received in a pivotbushing carried by the base 43, and which at its outer end Vis received in a pivot bushing carried by a plate, not shown, adapted to be secured by screws at 46, 46 to the upstanding lugs 41, 41 molded integral with the base 43. These lugs are provided with pins 48, 48 registering in holes in the plate nicely to determine "the iocation of the pivotal axis o1' the toggle member 44.

Adjacent its other end the toggle element 44 carries a tubular member 49 in which is longitudinally movable the piston 50 between whose lower end and the lower end oi.'- the member 49, within the latter, is confined a Spring 5| under compression. The complemental toggle element 52, illustrated as a metal disc having a peripheral knife edge, pivots in a recess in the upper end of the plunger 50 and also in a pivot recess in the metal post 53 xed to the base or Piate member 43.

The toggle structure described is of the gensulating material.

eral construction and mode of operation of that described in connection with Fig. l, producing a snap action as the member 44, through the contacts, is forced to right or left by the frame. Upon the member 44 is secured the contact 20a which, like contact 2|) of Fig. 1, comprises portions or elements disposed on opposite sides of member 44 for coaction with the frame contacts 2|a and 22a mounted, respectively, on screws 2lb and 22D threaded through the metal sides 55, 56 of the frame and held in adjusted position by the lock nuts 2|c and 220, respectively. Th-e contact 20a is connected to the binding post 54 through conductor 26a, and thence by a contnuing conductor, not shown, connected to the binding post 54 to the external circuit. The conductor 26a connects to a clip 2Gb, at a point thereof adjacent the pivot 45, and the clip is itself secured to the member 44 by screw 26C.

The frame comprises the aforesaid arms or side elements 55, 56, disposed on,opposite sides of the toggle, and so enclosing or embracing it. At their upper ends the frame elements 55, 56 are rigidly secured together by the tie member 23a of insulating material; at their lower ends they are secured by screws 51, 51 to the lugs 58, 58 integral with the frame block 59 of molded in- The block 59, side elements 55, and tie member 23a constitute a unit, movable as such about the pivot 60 carried by the downward extension of the block 59 and bearing at its inner end in a pivot bushing carried by the base 43 and at its outer end in a pivot bushing carried by a plate, not shown, adapted to be held by screws 6|, 6| threaded into the upstanding lugs 62, 62 of insulating material molded integral with the member 43. In the lugs 62, 62 are disposed pins 63, 63 for nicely determining the position of the plate and therefore the pivot 60.

To the binding posts 64 and 65 may be attached the external circuit conductors, not shown, which then communicate through the binding posts and the conductors 66, 61 with the conductor clips 66a: and 61a which are held by aforesaid screws 51, 51 against and in electric communication with the metallic frame members 55, '56 which, in turn, electrically communicate with the aforesaid contacts 2|a and 22a.

Attached at its one end to the eye 68 carried by the frame member 56 is the spring 69 whose other end is held by the posts 10 carried by or molded in the base 43.

The spring69 is under tension, exerting a force upon the frame, causing it to move or tend to move clockwise about its pivot 6U.

When otherwise free to do so, the spring 69 moves the switch to the position illustrated, in which the upper end of the toggle member 44 has snapped to the right, bringing contact 29a into engagement with contact 22a. n

The limits of travel of the frame are determined by the screws 1|, 1| threaded through the aforesaid post or lugs 41, 41. The screws are heid in their adjusted positions by the lock. nuts Ha, 1|a, and the inner ends of the screws are frame stops corresponding with the stops or beads 29a and 30a of Fig. 1. The impacts of the frame members 55, 56 upon the stops "ii, 1| eieot the jars or hammer blows having the nection with Figi.

The rod 3|, generally of metal, extends loosely through the tail of frame .block 55, and upon the tail of the block, to one side pivot 56, are

eiects of the stops 29a and 36a hereinbefore described in conV mounted, on opposite sides of the rod 3|,\abut ments or knife-edge blocks 12, generally of metal, against which bears the metal collar 13 on the metal bushing 14 which extends through and is rotatable in a hole in the right-hand lug orl block 62. The bushing 14 is threaded on the rod 3| and is rotatableby the manually operable knob 15 secured to the bushing 14 and having in its face parallel to the, outer face ofthe righthand block 62 an arcuate slit into which extends the end of the pin 16, carried by block 62, for limiting the rotation of the knob 15 and bushing 14 tov an angle of about 360, which extent of rotation of the bushing is generally sufiicient for the desired range of adjustment, which is dependent -upon the pitch of the threads of the rod 3| and bushing 14.

The rod 3| at its left-handportion is of rectangular cross-section, movable to the right and left within a rectangular hole in the left-hand block 62, or in a plate held thereby, whereby the I rod 3| is held against rotation.

As in the case of Fig. 1, the helical spring 42, surrounding the left end of the rod 3|, is confined between the head 4| on the rod and one face of the left-hand block 62 or. the aforesaid plate held thereon. The spring 42 exerts a force on the rod 3| causing it to move toward the left, and that force is communicated through the aforesaid collar 13 to the knife-edge block 12 canied by the frame.

When the pressure in the space about the/ sylphon .31, within the chamber 39, increases, the sylphon exerts a force toward the right on the, head 4| of the rod compressing the spring 42, so diminishing the force exerted by the collar 13 upon the knife-edge block 12 of the frame, and so permitting the spring 69 to actuate the switch to the position illustrated. Upon decrease or subsidence of the pressure within the chamber 39, the spring 42, gains control, causing the collar 33 to thrust more strongly against the knifeedge block 12 of the frame and so actuate it,

. in opposition to spring 63, to cause the switch to moveto its other position, corresponding with engagement of the frame` member 56 with the stop screw 1| at the left.

accesos By rotating the knob 15, the bushing 14, to

which it is secured, is adjusted .to the right or left upon the rod 3|, so adjusting the relation to each other of springs 42 and 69 to determine at what temperature, pressure, or other magnitude of the condition the switch shall be controlled or actuated, and particularly at which it shall be actuated to the position illustrated, under the then predominating inuence of spring 69.

As in the case of Fig.v 1, the force applied to the snapaction or toggle stru'cture is transmitted through the contacts, which are non-chattering and wipe upon each other.

The toggle elements 4 and 44 are preferably rigid or insubstantially iiexible, and the frame members I4, l5 and 55, 56 are preferably rigid, though they may be to substantial extent yielding or iiexible.- In the examples illustrated, all

the like toeiect control in opposite sense; which is to say, that' there is a d iierence or diierential between the pressures, temperatures or the like at which the snap action occurs inits respectivedirections of operation.

`Under differing conditions and circumstances such diierential may be necessarily or desirably greater or less. To adjust or vary such differential, various adjustments may b e made inthe apparatus shown.

The extent or magnitude of the diiierential may be adjusted by adjusting the amount or extent of lost motion betweensuitable or certain parts of the structures. For example, in Fig. 1 either or both of the stops or abutments 29a and 36a may be adjusted inwardly or outwardly to allow and procure the desired extent or amount of lost motion, and so adjust the magnitude of the diierential; and in Fig. 2 the adjustment of the magnitude of the differential may be e'ected by adjusting inwardly or outwardly either or both of the abutments or stops 1|. In both cases such adjustments of the' stops or abutments, or either of them, adjust theamount of permissible pivotal motion of the frame members |4 and I5, Fig.

1, and the frame, Fig. 2, whose side elements are ,f cured in any of the manners aforesaid or equivalents thereto, the greater will be the dieren'tial.

What I claim is:

1. A snap action switch comprising a4 member adapted to snap to positions on opposite sides of dead-center, a pivoted frame comprising members disposed on opposite sides of said iirst-named member, a contact carried by said rst-named member, contact structure coacting with said con'- tact and carried by said frame, a spring exerting a force on said frame to actuate it and thereby to actuate said rst-named member through said contact and said contact structure, a second spring opposing and of less strength than said first-named spring for actuating said frame in opposite direction, means forV overcoming the force of said rst-named spring to produce operation of said frame by said second spring, and means for controlling the relative magnitudesr of the forces exerted on said frame by said springs.

2. A snap action switch comprising an elongated member pivoted at one end, and means connected to its opposite end for operating said mem-k ber with a snap action to positions on opposite -sides of dead-center, apivoted frame comprising members disposed on opposite sides of and extending lengthwise jof said rst-named member generally parallel thereto, a contact carried by@ said first-named member adjacent-said operating means, contact structure coacting with saidicontact and carried by said frame, a spring exerting on said frame at a point spaced from its pivotal axis, a forcev to actuate it and thereby to actuate said iirst-named member through said contact and said contact structure, a second spring opposing and of greater strength than said first-named spring, means for exerting a force on said second spring to permit said firstnamed spring to actuate said frame, and means for varying the relative magnitudes of the forces exerted upon said frame by said springs.

3. A snap action switch comprising a member adapted to snap to positions on opposite sides of dead-center, a pivoted frame comprising members disposed on opposite sides of said member, coacting contacts carried by said member and said frame, a spring for actuating said frame in one direction, a rod extending free of said frame from one side to the opposite side thereof, an abutment of restricted contact area on said frame, a. coacting abutting member on said rod, a spring opposing and of greater strength than said firstnamed spring and exerting a force on said frame Patent No 2,096,709.

through said abutment and abutting member, and means for applying to said rod a force in opposition to said second-named spring.

4. A snap action switch comprising a member adapted to snap to positions on opposite sides of dead-center, a unitary frame comprising members disposed on opposite sides of said rst-named member, contacts carried by said first-named member and said frame, a pivot for said unitary frame, a rod extending loosely through a portion of said frame, a member on said rod abutting against one side of said frame, a spring on the opposite side of said frame from said abutting member for transmitting therethrough to said frame a control force, a second spring for actuating said frame in one direction and overcome by said rst-named spring for actuating said frame in opposite direction, and means for exerting on said first-named spring a force overcoming said control force to produce actuation of said frame by said second-named spring.

JOHN STRUTHERS DUNN.

CERTIFICATE CE CORRECTION.

October 26, 195'? JOHN STRUTHERS DUNN.

(sul) ing correction as follows: Page 5,' first dth". re ad switch;

and that the -said Let'- orrection therein that the same may the Patent Office. December., A. D. 1957.

Henry Van Arsdale, Acting Cpmmissioner of Patents. 

